Electronic assemblies having more than one printed circuit board or card need to have a means of interconnecting the circuit boards to each other. In some instances, cables are used to achieve these interconnections, each interconnection requiring a connector on one or both ends. Connectors are used to permit the functional units, such as cards or circuit boards, to be individually inserted and removed for reasons of testability, manufacturing costs, repair, and changes for upgrading equipment or installation of optional features in the field. A connector is typically defined as a device to repeatedly separate and reconnect pathways in an electronic system. The connector provides a separable interface between the boundaries of two electronic elements. These electronic elements may be different, similar, or identical. Connections between printed circuit boards and flex circuits are also widely used. In connecting two or more printed circuit boards, a mother/daughter board connection is typical.
In order to separably connect an element or printed circuit board A to element or a second printed circuit board B, there are typically three interfaces that must be satisfied, each of which must provide a signal path and an appropriate mechanical structure. The first interface connects the first printed circuit board to a connector, the second interface connects the first connector to a second connector and the third interface is between the second connector and the second printed circuit board. Implicit in the requirement for a separable connection, the connecting system must also have the following capabilities. 1) fit the elements to be connected, 2) align the elements, 3) actuate the connection, 4) satisfy the performance specification, 5) resist the forces which could degrade the connection, 6) permit contact separation when required, 7) survive in superior operating order for the product life, and 8) provide good electrical performance.
Typically, in connecting two printed circuit boards, a card-edge connector or similar device is used. The card-edge connector is typically a plastic component with numerous electrical contacts which are soldered directly to a printed circuit board. The second printed circuit board may be inserted directly into the card-edge connector or it may have an additional corresponding connector soldered to it; in the second case, the two connectors are plugged together so as to provide a mechanical and electrical interconnection between the two circuit boards. Special types of connectors are used when connecting flexible films, such as flex circuits, to each other or to rigid circuit boards, and still other types of connectors are used when connecting cables to printed circuit boards.
In each of these situations, at least one or more additional components is required to interconnect the circuit boards. Interconnecting circuit elements using conventional means extracts a penalty in terms of space, volume, cost, complexity, and labor required to build the assembly. It would be advantageous if a scheme were devised that would completely eliminate the need for these connectors, and still provide a physical and electrical interconnection between one or more circuit boards. The elimination of these connectors would provide a significant advantage to the electronics industry in reducing the complexity, size, and cost of electrical interconnections in devices such as computers and other consumer electronic gear.